Self-locking hydraulic linkage



A. R. s'roNE 2,387,307

Filed June 16, 1942 M F V l l l l SELF-LOCKING HYDRAULIC LINKAGE Ud. 23, i945.

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Patented Oct. 23g, 1945 UNI-TED STATESQPATENT GFI-"CE SELF-LOCKING HYDRAULIC GE Anbei-t Rivingmn stone, Belair, Ma. Application .rune is, 1942. lserai No. 441,269

' a claims. (ci. eci-s2) (Granted .under the act of March 3, 1883, an

ended Aprii 30, 1928; 37A@ G. 57)

`is Inot operating, the motor is held immovable against possible reactive forces thereon. A further object of the invention is to provide. a novel valving system which is operated in response 'to intentional actuation of a hydraulic pump but which may not be operated by reactive forces upon a hydraulic motor. Still another object of the invention is to provide a. check` valve system in a hydraulic circuit and to provide fluid pressure responsive means to operate the check valves under certain operating conditions of the system. Y The details of the invention may be better understood by referring to the detailed description below in connection with the drawing in which: s v

Fig. l is a 'diagrammatic elevation showing a hydraulic system, and

Fig. 2 is an enlarged section of a hydraulic valve unit which is the essence of the invention.

Referring to the drawing, in Fig. 1 I show the hydraulic motor M ofthe piston-cylinder type to the ends of which conduits li and l2, are connected. By feeding liquid to the conduit i i, the piston is moved to the right and by feeding liquid to the conduit i2, the. piston is moved to the' left. Low pressure duid is exhausted from the other conduits in either of the above cases. These conduits connect through a valve unit i3 through conduits iii and It leading to a reversible `pump P which may be driven by any suitable means.A

Obviouslmby turning thepump in one direction the motor is operated in one direction, while turning the pump in the other direction operates the motor in the other direction. The valve unit i3 is soarranged that pressure uid may ilow from the pump to the, motor when the pump is .operated intentionally; otherwise, the motor is y hydraulically locked by the valve so that external forces applied thereto will not operate the pump.

I also contemplate using a plurality of pumps such as P and P", with valves I3' and i3 between them and the motor conduits il and i2 so that the motor may be operated from any one of the several pumps.N When any one pump ceases operation the hydraulic motor is locked in the adjusted position. Further movement of the motor in either direction, however, may be secured by operating any other of the several Pumps- The valve i3 (as well as it and l3") serves to allow the above selective pump operation and serves the further function of isolating the motor system should any one or the pumps and their associated conduits it and i5 become inoperative for any cause.. For instance, if the hydraulic Vsystem of Fig. l was applied to a combat vehicle or military aircraft for operation of accessories, so long as the closely associated motor and valves it are intact, the system will not he wholly -bled of hydraulic fluid should any one oi the pumps or lines it and it be shot away.

Referring to Fig. f2, a valve body it has formed therein coaxial hores i9, 2d, and 2i, the bore 2t.

being of smaller diameter than the end bores i@ and 2i. Through the bore 2d, a piston rod 2t passes in rather closely tted relationship. To each end of the piston rod t is secured, as by a' snap ringA 2t, pistons 25 and 26 which are tted closely to the bores it and 2i respectively. These pistons have formed therein amai passages 2 to permit free dow of uidbe the piston ends.l

.at the vright hand port 39 communicating with an opening .3l to which oneof the pump conduits such as it is connected. Ati-the left hand end of the bore 2l is a port 32 communicating with an opening t@ to which the other pump conduit such as it is connected. lGovered, at times, by the pivstons' 215 and '28, are ports et, .3?. and te, '39 respectively. The ports 36 and te are closed by ball check valves tt and tl respectively. The ports 3S and 3l communicate with an opening t to which one of the motor lines such as iiis connected, while the ports t@ and 3@ communicate with an opening de to which the other motor conduit such as' 82 isconnected.

At'the outer ends of the hores i9 and 2i.

centering spring assemblies te are secured as by snap rings el. The spring assemblies it 'form closures for their bores and inciude ring packings 38 to seal them in the bores. The centering springs serve to hold the piston assembly 23, 25, and 26 in a normally contrai position where 'the piston 25, covers both ports 3S and 3l and where the piston 2S covers both ports 38 and 39.

The operation of the valve unit is as follows: Ii. uid under pressure is admitted to the port t@ by pump operation., the presser-e huid will act end of the bore i9 is aI upon the left hand end of the piston rod 2|! and will move the rod to the right, carrying the pis#- tons and 26 with it and compreming the right hand spring unit 46. Thus, the port 36 will be opened to the port and pressure iiuid may flow past the check valve to operate the motor. Likewise the piston 26 will uncover the port 39'to permit free fl'ow of .low pressure fluid from the motor to the vpump intake through the port 32. In this situation, should a large reactive force be imposed upon the fluid motor' tending to prevert pump operation or to reverse the pump, the check valve 4D will close preventing the transmission of the fluid force to the pump, at least until such time as the fluid pressure of the pump exceeds that existing in the opening 43 of the valve.

If the pump lis reversed. the piston rod 20 with its associated parts will move to the left, opening the port 32 to the port 38 and the port 30 to the port 31, thereby allowing reverse motor operation while maintaining the safety features above outlined. At any time when pump operation ceases, the centering spring units 46 will centralize the piston assembly, by virtue of slight leakage between the piston 23 and the bore 20 closing the ports 36, 31, 38 and 39, locking the hydraulic motor M from movement, and furthermore, locking the hydraulic uid in the motor conduits in such a way that failure of the pump P will not bleed the motor system of fluid and allow it to collapse. The use of a `plurality of valve units and pumps allows operation of the motor from a plurality ci distant points and the motors` may be operated individually or jointly and will always be divorced from the motor system as soon as pump operation ceases.

It will be apparent from the above description that the objects of the invention are met and that the-valve unit described provides automatic and positive isolation of a hydraulic motor system from a pump under all conditions except when the pump is operated intentionally.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modiiications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modiflcations and changes.

I claim:

1. A control valve for use in a pair of pressure conduits connecting a revers'lblepump and a reversible hydraulic motor, said control valve comprising a housing, said housing having a, bore extending axially therethrough, a piston slidably reciprocable in said bore, said piston and said bore being of such relative sizes that cavities are provided at the opposite ends of 'said bore and said piston blocks any passage of fluid through said bore between said cavities, one cavity havingV a port connecting it to the pump-side of one pressure conduit, the other cavity having a port connecting it to the pump-side of the other presl sure conduit, a passage-way in said housing connected to the motor-side of one pressure conduit, a second passageway connected to the motorside of the other pressure conduit, a pair of ports connecting one cavity to one passageway, a second pair of ports connecting the second cavity to the second passageway, plug means closing the outer end of each cavity, yieldable means urging said piston to a middle position, a. sleeve valve in each said cavities at each end of and con."l

nected to said piston, each said sleeve valve closing both motor-side ports when said piston is in said middle position, said piston sleeve valve being limited in its reciprocation to open either but not both of eac-h pair of motor-side ports, said pump-side 'cavity ports being always open, a one-way cavity-exit-valve on one port of each pair of passageway ports, said sleeve valves permitting communication through only one cavityexit-valve port and simultaneously through the other motor-side port of the second cavity at one time, whereby high pressure fluid from the pumpside of one of the pump pressure conduits holds the piston and sleeve in communication-permitting-position through the cavity-exit-valve port to permit flow of high pressure fluid therethrough to one motor-side passageway and simultaneouslyl low pressure uid to ow from the other motor-side passageway back to the to the other pressure pump conduit, and whereby reverse flow on the motor-side of the passageway receiving high pressure from said pump causes said one-way cavity-exit-valve to close and permit said yieldable means to reciprocate said piston sleeve to low pressure port-blocking position While the cavity-exit-port valve closes the high pressure port of the same cavity, thereby only permitting passage of high pressure from the pump-side to the motor-side and locking off passage of high pressure from the motor-side to the pump-side. I.

2. A control valve for use in a pair of pressure conduits connecting a reversible pump and a reversible hydraulic motor, said control valve comprising a housing, said housing having a bore extending axially therethrough, a. piston slidably reciprocable in said bore, said piston and said bore being of such relative sizes that cavities are provided at the opposite ends of said bore and 'said piston blocks any passage of iiuid through said bore between said cavities, one cavity having a port connecting it to the pump-side of one pressure conduit, the other cavity having a port connecting it to the pump-side of the other pressure conduit, a passageway in said housing connected to the motor-side of one pressure conduit, a. second passageway connected to the motorside of the other pressure conduit, a pair of ports connecting one cavity to one passageway, a second pair of ports connecting the second cavity to the second passageway, plug means closing the outer end of each cavity, yieldable means urging said piston to a middle position, a sleeve valve in each said cavities at each end of and connected to said piston, each said sleeve valve closing both motor-side ports when said piston is in said middle position, said piston sleeve valve being limited in its reciprocation to open either but not both of each pair of motor-side ports, said pumpside cavity ports being always open, a one-way cavity-exit-valve on one port of each pair of passageway ports, said sleeve valves permitting communication through only one cavity-exitvalve port and simultaneously through the other motor-side port of the second cavity at one time, whereby high pressure fluid from the pump-side of one ofthe pump pressure conduits holds the piston and sleeve in communication-permittingpositionv through the cavity-exit-valve port to permit flow of high pressure fluid therethrough to one motor-side passageway and simultaneouslyiow pressure uid to' ilow from the other reverse iiow on the motor-side of the passageway receiving high pressure from said pump causes said one-way cavity-exitvalve to close and permit said yieldable means to reciprocate said piston sleeve to low pressure port-blocking position whilekthe cavity-exit-port valve closes the high pressure port oi the same cavity, thereby only permitting passage of high pressure from the pump-side to the motor-side and locking ot! passage o! high pressure from the motor-side to th pump-side. v

3. A control valve i'or use in a pair of pressure conduits connecting a reversible pump anda reversible hydraulic motor, said control valve comprising a housing. said housing having a bore extending axially therethrough. a piston slidably reciprocable in said bore. said piston and said bore being o! such relative sizes that cavities are provided at the opposite ends oi said bore and said piston blocks any passage oi iiuid through said bore ,between said cavities, one' cavity having a only permitting passage oi. high pressure from the pump-side .to the motor-side and locking oi! passage oi high pressure trom the motor-side to the pump-side.

4. A control valve i'or'use in a pair o! pressure conduits connecting a reversible pump and are versible hydraulic motor, said control valve comprising a housing, said housing having a bore having a reduced central neck extending axially therethrough, a piston slidably reciprocable in said bore neck, said piston and said bore being port connecting it to the pump-side oi one pressure conduit, the othercavity having a port connesting it to the pump-side oi' the other pressure conduit, a passageway in said housing connected to the motor-side o! one pressure conduit, a second passageway connected to the motor-side of the other pressure conduit, a pair oi ports connecting one cavity to one passageway. a second pair oi ports connecting the second cavity to the second passageway, plug means closing the outer end oi each cavity, spring means based on said.

plug means urging said piston to a middle position, a sleeve valve-in each said cavities at each end of said piston. spider means connecting each said sleeve valve toits end of said piston. each said sleeve valve closing both motorfside ports oisuch relative sizes that cavities are provided at the opposite ends 'of said bore and said piston blocks any passage o! huid through said bore neck between said cavities, one cavity having a port connecting it to the pump-side of one pressure conduit, the other cavity having a port connecting it to the pump-side oi the other lpressure v conduit, a passageway in said housing connected to the motor-side ot one pressure conduit, a second passageway connected to the. motor-side oi the other pressure conduit, a pair oi ports connecting one cavity to one passageway, a second pair of ports connecting the second cavity to the second passageway. plug means closing the outer end o! each cavity, yieldable means urging said piston to a middle position, a sleeve valve in each said. cavities at each end of and connected to said piston, each Asaid sleeve valve closing both 4motor-side ports when said piston is in said middle position. said piston sleeve valve boina lim?.

' ited in its reciprocation to open either but not both when said piston is in said middle position, said piston .sleeve valve being limited in its reciprocatonto open either but not both o! each pair ot being always operi,Y a one-way cavity-exit-valve on one port oi each pair oi passageway ports, said sleeve valves permitting communication through only4 one cavity efxit valve port -and simultaneously through the other motorside port of the secondcavity at one time, whereby high motor-side ports, said pump-side cavity ports oi each pair oi motor-side ports, lsaid pump-side cavity ports being always open. a one-waycavityexit-valve on one port of each pair o! passage-` way ports, said sleeve valves permitting communication through only one cavity-exit-valve port and simultaneously through the otherv motor-side port ot the second cavity at one time, whereby high pressure duid from the pump-side oi one of theV pump pressure conduits holds the piston and sleeve in communication-permitting-- position through the cavity-exit-valve port to 45 permit ilow'oi high pressure duid therethrough pressure uid from the pump-side of one of the to one motor-side passageway and simultanei ously low nuid to ilow trom the other motor-side passageway back to the other pressure pump conduit, and whereby high pressure on the motor-side ot the passageway receiving v I reverse now trom said pump causes said one-way cavity-exit-valve to close and permit said yieldable means to reciprocate said piston sleeve to low pressure port blocking Mision while the 55 cavityexitport valve closes the high pressure wenn position while cavityeritport valve cloaca port of the same cavity. thereby only permitting passage oi high pressure from the pump-side to the motor-side and locking oi! passage od high fromthemotorfsidetothepumpdide.

mn l ALBIRT mam STUNI.'

the high pressure porto! the same cavity. thereby 

